Quick connectors are used widely for connecting tubes serving as automotive fuel lines. The quick connector is capable of simply and quickly connecting tubes without using any fastening means, such as bolts. The quick connector has a connector housing to be attached to one of two tubes, and a retainer to be pressed in the connector housing after inserting the other tube in the connector housing to retain the tube in the connector housing. Representative quick connectors are disclosed in Patent documents 1 and 2.
In some cases, the retainer is pressed into the connector housing before the other tube is fitted in the connector housing. If the retainer is pushed into the connector housing before pressing the retainer into the connector housing, the tube is connected incompletely to the quick connector. Such incomplete connection of the tube to the quick connector cannot be distinguished from complete connection by appearance.
A quick connector disclosed in Patent document 3 is designed to enable the recognition of such incomplete connection of the quick connector and a tube at a glance. This quick connector includes a complete connection indicating member in addition to a retainer. The complete connection indicating member cannot be easily removed from the quick connector unless the tube is inserted correctly in the quick connector and the retainer is engaged correctly with the tube.    Patent document 1: U.S. Pat. No. 5,542,716    Patent document 2: JP 2002-206683 A    Patent document 3: JP Hei 11-230456 A